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Technical Paper

Numerical Investigation of Narrow-Band Noise Generation by Automotive Cooling Fans

2020-09-30
2020-01-1513
Axial cooling fans are commonly used in electric vehicles to cool batteries with high heating load. One drawback of the cooling fans is the high aeroacoustic noise level resulting from the fan blades and the obstacles facing the airflow. To create a comfortable cabin environment in the vehicle, and to reduce exterior noise emission, a low-noise installation design of the axial fan is required. The purpose of the project is to develop an efficient computational aeroacoustics (CAA) simulation process to assist the cooling-fan installation design. This paper reports the current progress of the development, where the narrow-band components of the fan noise is focused on. Two methods are used to compute the noise source. In the first method the source is computed from the flow field obtained using the unsteady Reynolds-averaged Navier-Stokes equations (unsteady RANS, or URANS) model.
Technical Paper

Front-Wheel Drives

1930-01-01
300001
ENGINEERING considerations leading to the former almost universal practice of steering with the front wheels and driving and braking with the rear wheels are reviewed, and the desire for bodies lower than can be made with conventional design is given as the main reason for the present interest in front drives. For early history, European development, racing practice and the closely related subject of four-wheel drives, the reader is referred to a previous paper by Herbert Chase.2 One major advantage to be secured with front-drive design is lower unsprung weight, which should promote easy riding and road-holding ability and reduce tire wear. An inherent disadvantage is that driving-torque reaction and hill climbing shift some weight from the front axle to the rear axle, thus slightly reducing the tractive effort possible; but this shift is not considered important, since the control of weight distribution is in the hands of the designer.
Technical Paper

Engine Cooling

1932-01-01
320063
FROM 25 to 35 per cent of the heat energy of the fuel inducted into the cylinders of an internal-combustion engine must be eliminated by the cooling system. As this waste requires the expenditure of energy, the devising of an efficient cooling system is imperative. The author, who is a leading American authority on engine problems, discusses the theory of liquid-cooling, gives heat-transfer and temperature-balance equations that must be satisfied and points out the three interrelated variable factors that must be incorporated in their most economical relation. The cooling system must be studied as a whole, rather than from the standpoint of any particular unit. Some commonly held beliefs regarding fans, fuel-pumps and oil-temperature control are controverted. Five elements necessary for an efficient cooling system are enumerated.
Technical Paper

Frame Design and Front-End Stability

1932-01-01
320003
EXPERIMENTAL work done to ascertain the influence of frame and body structures upon front-end stability of the automobile is described by the author and definite means of preventing the phenomena of wheel wabble, shimmy and vibratory movements of the radiator, head-lamps and fenders are set forth. Early investigation showed that the problem involved not only the unsprung portions of the car but also the structural arrangement of the frame and the body. Chassis-dynamometer tests revealed a nodal point of zero torsional vibration approximately at a plane through the front seat but varying with different cars and body types, the forward portion of the chassis vibrating torsionally about the longitudinal axis in opposite phase to the rear portion. Experiments rather conclusively proved that damping is needed in the frame and body.
Technical Paper

Gaging Airplane-Engine Performance

1930-01-01
300036
WHILE virtually all aircraft builders agree in placing reliability as the most important factor in gaging engine performance, from there on agreement is lacking. The author believes that all factors exclusive of reliability can be evaluated so as to provide a good basis for choosing an engine. These factors include durability, which despite the opinion of some aeronautic engineers is not synonymous with reliability; weight per horsepower of the complete powerplant, including radiators and cowling; head resistance; fuel consumption; and first cost. The effect of changes in engine weight on operating cost are discussed, the text being supplemented by tables showing the effect of increased engine-weight, operating cost and the operation-expense items that are affected.
Technical Paper

Development of the Franklin Direct Air-Cooled Engine

1931-01-01
310004
FEATURES of the design of the various cylinders built by the Franklin organization in its development program leading up to the present design are discussed in this paper. The relation of waste heat to cooling-fin areas and cooling-blast velocities is shown and discussed for cylinders up to 3½-in. bore. Characteristics of the cooling system, including fan, fan housing and air housings, are discussed at length, and the authors contend that no more power, if as much, will be absorbed in the cooling system as in that of the indirect air-cooled engine. Results of tests showing the ability of the engine to cool under the severest conditions of load and temperature are given. Since the quietness of any engine is dependent upon constant valve-clearances, the authors describe in detail the method followed in the Franklin design to maintain at less than 0.003 in. any variation in clearance. A careful analysis is made for each part in the valve-gear mechanism that is affected by expansion.
Technical Paper

Reducing Horsepower and Noise of Automotive Cooling-Fans

1931-01-01
310014
STATING the automotive cooling-fan problem as being constituted of the delivery of more air, decrease of fan horsepower, reduction of fan noise so that it is comparable with or less than other powerplant noises and the installation of the fan in a restricted space, the author describes the testing apparatus and method used in analyzing the subject. Fan speeds and the most effective number of blades are then considered, followed by analyses of fan diameter and pitch and curvature of fan blades. The manner in which air is discharged from the fan and the adaptation of a fan to an automobile are also discussed. Following statements concerning the desirable number of fan blades and blade spacing, noise characteristics of fans are analyzed in detail as a preface to the author's consideration of means of reducing fan noise, and a summary listing the conclusions reached as a result of the study is appended.
Technical Paper

Recent Developments in Poppet Valves

1931-01-01
310007
AFTER stating that increased speed, mean effective pressure and piston displacement of engines have made valve conditions more difficult during the last few years, the author recalls the path which development has followed by a brief list of materials and methods of cooling. Where the stem joins the head is the hottest part of the valve. A shield for this point is shown, also a shroud to protect the end of the valve-stem guide. Cooling the valve increases its life. Salt and sodium cooling are compared, and methods of sealing the coolant in place are described. The construction and behavior of copper-cooled valves are illustrated and recounted, and a one-piece hollow-head valve is described. Reasons for valve-seat inserts are given.
Technical Paper

The Cooperative Fuel-Research Committee Engine

1931-01-01
310019
AFTER stating the three qualifications that should be possessed by a fuel-testing engine as (α) universality, (b) ruggedness and (c) low cost, the way in which all are met is outlined. The construction of the original engine is described in some detail and a table of dimensions of the more important parts given. Refinements that were developed as a result of work with the original engine in the last 2 years affect water-jacketing, condenser-coil location and accessibility of certain parts. To overcome objections raised as a result of actual experience in fuel testing by members of the Cooperative Fuel-Research Committee, the engine has been recently redesigned to include a variable-compression cylinder, a modified centrifugal type of water pump and magneto-ignition. These changes are described and the reasons for their incorporation in the engine are stated. Illustrations and drawings showing various stages in the development of the engine supplement the text.
Technical Paper

ENGINE-COOLING SYSTEMS AND RADIATOR CHARACTERISTICS 1

1924-01-01
240013
In the first part of the paper, a general quantitative comparison of air, water and oil-cooled cylinders is given as it relates to the subject of heat-transfer and temperature drop. Unfortunately, the discussion does not include experimental data, but the assumptions are stated clearly and a large range of values is covered in Table 2 so that any desired values can be chosen. A thorough and comprehensive discussion of the steam or the radio-condenser type of cooling is given under the headings of Steam Cooling Systems, Characteristics of Steam Cooling Systems, Cooling Capacity of Radiators Used To Condense Steam and Present State of Development. In the second part, an attempt is made to give a thorough but brief discussion of the performance or of the operating characteristics of radiators from the point of view of the car, truck or tractor designer. The cooling of aircraft engines is not considered.
Technical Paper

ENGINEERING BRAINS IN FLEET OPERATION1

1923-01-01
230056
The magnitude of the business of the American Railway Express Co. requires that careful consideration be given to the details necessary for economical operation. The equipment comprises 12,755 vehicles, of which approximately one-third are motor-driven and have a carrying capacity of more than one-half the total. On July 1, 1918, when all the express companies were merged into one organization, it was found that the motor-vehicle equipment included 59 different makes and 131 different models. Among the 377 trucks built by one company were 21 different models. Diversity of equipment, of course, complicates the maintenance problem and adds to the cost. Additional expense is incurred frequently by purchasing and experimenting with parts offered by makers of accessories such as carbureters, spark-plugs, wheels and the like. Careful inspection, adequate lubrication and the adoption of “stitch-in-time” methods will save needless expense.
Technical Paper

COOLING CAPACITY OF AUTOMOBILE RADIATORS

1923-01-01
230012
Annual Meeting Paper - The heat-dissipating properties of three types of radiator core have been investigated at the Mason Laboratory, Yale University. These include the fin-and-tube, the ribbon and the air-tube groups, so classified according to the flow of the water and the air. The ratio of the cooling surface to the volume is shown to be nearly the same in the fin-and-tube and the air-tube cores, while that of the ribbon core is somewhat greater. A formula is derived for computing the heat-transfer coefficient, which is defined as the number of heat units per hour that will pass from one square foot of surface per degree of temperature-difference between the air and the water and is the key to radiator performance, as by it almost any desired information can be obtained. When the heat-transfer coefficients have been found for a sufficiently wide range of water and air-flows the cooling capacity of a radiator can be computed for any desired condition.
Technical Paper

IMPROVED NICKEL-PLATING METHODS

1924-01-01
240053
A practical method of nickel-plating is outlined and the various processes are described by which the Packard Motor Car Co. has been successful in producing a durable coating of nickel on automobile parts in general, and the radiator shells, the rim plates and the tire-carrier plates, in particular. These are the parts of greatest exposure, and for plating them a new system of moving-cathode tanks was installed. The three problems to which special attention was devoted were rusting, pitting and peeling. No effort was made to secure a coating of any designated depth but reliance was placed solely on the results indicated by a 24-hr. salt-spray test, which was considered to be the equivalent of 2 years' exposure to the usual weather conditions. Peeling was overcome by thoroughly cleaning the parts before plating. New equipment was purchased and laid out in accordance with the system decided upon, namely, copper-plating, buffing and nickel-plating.
Technical Paper

RECENT AEROPLANE-ENGINE DEVELOPMENTS

1916-01-01
160025
The author gives a brief review of developments during the past year in the construction of aeroplanes, particularly as affected by the European War. He takes as an example the Renault twelve-cylinder engine, citing the respects in which the present differs from previous models. Such factors as the changes in cooling systems, method of drive, valve construction and starting devices are considered. The requirements of aeroplane engines, such as constant service, high speeds (of aeroplanes) and stream-line form of engines and radiators, are outlined. Propeller requirements are dealt with at length, curves being given by which the efficiency and diameter of the propeller can be obtained. In conclusion a number of different engine installations are illustrated and compared.
Technical Paper

HIGH OPERATING-TEMPERATURE AND ENGINE AND CAR OPERATION

1926-01-01
260016
This subject is treated in a paper in two parts. Part I, by Alex Taub, deals with laboratory tests to prove by comparative data that the higher average operating-temperatures maintained in the engine by the constant-temperature, or evaporation, system of cooling have negligible detrimental effects. Part II, by L. P. Saunders, gives the results of road-tests of cars operated under the same conditions when fitted with a standard water-cooling radiator-core and with a constant-temperature cross-flow condenser-core. Although contamination of the crankcase oil by heavy ends of the fuel is not prevented by the higher temperature of constant-temperature operation, it is asserted that this higher temperature is effective in striking an acceptable balance in such contamination and results of the tests show that the cylinder-walls are maintained at temperatures sufficiently above the vaporization point of water to reduce the condensation of water vapor to the minimum.
Technical Paper

Efficiency Test for Radiator-Fan-Type Air-Cleaners

1927-01-01
270038
SINCE air-cleaners of the radiator-fan type cannot be tested satisfactorily by the older method, in which a known weight of dust is fed directly into the airstream entering the air-cleaner, a special method was found necessary in which the air-cleaner under test is mounted in its normal position behind a radiator fan that is located inside of an elliptical wind-tunnel within which the fan circulates air. A tractor engine running at constant speed and load drives the fan in the wind-tunnel and draws the air for its carbureter from the wind-tunnel through the air-cleaner under test and an absolute air-cleaner connected in series. A 100-gram charge of a standardized dust is introduced into the wind-tunnel. By averaging the results obtained from repeated tests, using three different collecting-type dry centrifugal air-cleaners, it is found that under normal conditions 15 per cent of the total dust-charge actually reaches the air-cleaner under test in the described apparatus.
Technical Paper

Methods of Obtaining Greater Power from a Given Engine

1929-01-01
290011
DEMAND for increased car-performance forces manufacturers to provide more powerful engines. It is desirable to obtain the increased power without designing a new engine, particularly in the case of large-scale manufacturers. The author lists possible means of doing this as making increases in the speed, the volumetric efficiency, the compression ratio, the thermal efficiency and the mechanical efficiency; and explores each of these methods in the light of latest developments in engine design. Among the concrete suggestions are greatly increased valve-lift, hydraulic valve-gears, multiple car-bureters, injection of vaporized fuel into cold air, cutting out the fan at high speed, and the use of superchargers. Higher compression generally involves changes in cylinder-head design, which are covered in some detail. Subjects covered in the discussion include lubrication, roller-chain camshaft drives, form of combustion-chamber, availability of engine power, and two-cycle engines.
Technical Paper

Atmospheric Humidity and Engine Performance

1929-01-01
290033
SO-CALLED correction factors to compensate for variations in atmospheric temperature and pressure have been in practical use in connection with engine testing; but the influence of the varying amount of aqueous vapor present in the atmosphere has not had sufficient consideration. The author submits brief test-data indicative of the effect of humidity on some factors of engine performance and of the feasibility of using rational power-correction factors. By assigning due importance to the effect of humidity, he believes that a more satisfactory analysis of car and of engine performance can be obtained. Using a single-cylinder engine operated at full throttle and 1000 r.p.m. under stabilized conditions, tests were made observing maximum power, air-flow, fuel-flow, detonation and spark-advance requirements over a wide range of relative humidity for an air-intake temperature of 100 deg. fahr. Curves made from the data obtained are given and discussed.
Technical Paper

SOME ASPECTS OF AIRCRAFT-ENGINE DEVELOPMENT

1925-01-01
250066
Infallible performance and economical operation are the bases of successful commercial flying. Airplanes, having passed through the experimental and demonstration periods, must now prove their usefulness. Heretofore, because of military requirements, designers have fostered the use of power rather than refinement of design to obtain performance, but commercial operation demands efficiency, and in each of the four essentials, namely, dependability, size, total powerplant weight and cost, opportunity for decided improvement still exists. The requirements and limiting factors of each of these essentials are discussed in turn and the conclusion is drawn that a relation exists between the amount of thrust delivered to the air and the weight put into an airplane for its propulsion. To obtain the best over-all performance, if these terms are considered as a fraction, the numerator should have the maximum and the denominator the minimum value.
Technical Paper

DEVELOPMENT AND DESIGN OF HYDRAULIC-BRAKE UNITS1

1925-01-01
250045
The principles of hydraulics have long been known and the use of a liquid for transmitting power has proved safe and reliable in many applications, notably in the operation of passenger elevators. Hence it was natural to make use of these principles in a device for controlling an automobile under traffic conditions that demand an efficient and dependable braking mechanism. The ideal of equalized braking-effort is sought but variation in the coefficient of friction between brake-bands and brake-drums and between tires and road introduces complications, so we must be content for the present with the nearest possible approach to equalized pressure at the brake-bands. In the hydraulic system, pressure is transmitted equally throughout the liquid and to the levers that actuate the brake-bands. These levers are also designed to transmit the pressure equally to the brake-bands on all four wheels.
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